In the context of the present invention, “panel having built-in heat pipe(s) and/or insert(s) means a panel comprising plates called bottom and upper plates, between which heat pipes and/or inserts are immobilized (for example two or three, or even thirty or forty), separated from one another by separating structures, generally of the honeycomb type. Furthermore, in the context of the present invention, “insert” means a block, for example of aluminum, serving as a fastening point for equipment installed later.
As a person skilled in the art knows, such panels can be fabricated by two methods comprising numerous steps, starting with a flat plate (or baking plate), bottom and upper plates, heat pipe(s) and/or insert(s), pins and separating structures.
The first method consists in first treating the pins to coat them completely with a material for allowing their stripping. The bottom plate must then be placed on the flat plate and then coated with a layer of adhesive. The separating structures must then be positioned in selected places, in order to define accommodation zones for heat pipe(s) or insert(s). The heat pipes and/or inserts must then be positioned in the accommodation zones between the separating structures. Part of the free space between the heat pipes and/or inserts and the separating structures must then be filled with an intumescent adhesive. The upper plate (or an auxiliary plate) must then be placed above the heat pipe and/or inserts and separating structures and in contact therewith, after the lower face of the upper plate is coated with an adhesive layer. The treated pins must then be introduced through the upper plate (or auxiliary plate) so that they are placed in the spaces containing the intumescent glue on either side of the side faces of the heat pipes and/or inserts. The assembly (including the baking plate) must then be passed through a furnace or an autoclave for a selected period, in order to cure the panel. This is followed by stripping. The pins must then be extracted. And finally, the pins must be cleaned.
It may be observed that in case of the use of an auxiliary plate, the latter must then be removed by bonding to a final upper plate called “flying plate” (the use of an auxiliary plate serves to confirm the expansion of the intumescent adhesive without having to take X-ray pictures).
The second method consists in first treating the pins to coat them completely with a material that allows their stripping. The treated pins must then be positioned in places selected on the baking plate, corresponding to the accommodation zones of the heat pipes or inserts on the bottom plate. The bottom plate, previously coated with adhesive, must then be placed on the flat plate so that it is traversed by the pins. The separating structures must then be positioned between the alignments of pins outside the accommodation zones of the heat pipe or insert. The heat pipes or inserts must then be positioned in their accommodation zones between the alignments of pins. The free space between the heat pipes and/or inserts and the separating structures must then be filled with an intumescent adhesive. The upper plate (or an auxiliary plate) must then be placed above the heat pipes and/or inserts and separating structures and in contact therewith, after an optional coating of the lower face of the upper plate with a layer of adhesive. The assembly (including the baking plate) must then be passed through a furnace or autoclave during a selected period, in order to cure the panel. The panel must then be stripped by carefully separating the panel from the pins joined to the baking plate. The pins must lastly be cleaned.
This second method is currently preferred when the tolerance of the positioning of the heat pipes and/or inserts is low (typically above one millimeter). However, it is quickly limited in the case of a large number of heat pipes and/or inserts and a large panel.
Regardless of the method used, the number of steps in the sequence is too large and the extraction of the pins from the panel proves to be difficult, and even sometimes virtually impossible due to the action of the adhesive on the parts of the pins or housings thereof where the protection may be damaged during handling and/or which are poorly protected. It is certainly possible to improve the situation, for example by using taper pins and/or holes comprising a flat, but this increases the cost without necessarily reducing the number of steps in the sequence.